1. Field
Embodiments of the present invention generally relate to semiconductor processing equipment, and, more specifically, to inductively coupled plasma processing systems.
2. Description
Inductively coupled plasma (ICP) process reactors generally form plasmas by inducing current in a process gas disposed within the process chamber via one or more inductive coils disposed outside of the process chamber. The inductive coils may be disposed externally and separated electrically from the chamber by, for example, a dielectric lid. For some plasma processes, a heater element may be disposed above the dielectric lid to facilitate maintaining a constant temperature in the chamber during and between processes.
The heater may be an open break heater (e.g., a non closed electrical loop) or a no break heater (e.g., a closed electrical loop). In embodiments where the heater element is an open break heater element, the heater element introduces plasma non-uniformity that can result, for example, in non-uniform etch rates of a substrate being processed or asymmetry in the etch pattern. This plasma non-uniformity can be eliminated by replacing the open break heater element with a no break heater element. However, in embodiments where the heater element is a no break heater element, RF energy delivered to the inductive coils also inductively couple to the no break heater element, thereby undesirably reducing the energy available to form a plasma within the process chamber (e.g., the no break heater element reduces the plasma strike window).
Thus, there is a need for an improved inductively coupled plasma reactor.